This invention relates generally to die cutting apparatus and more particularly to such apparatus which is useful in making pressure sensitive labels of the type which may be peeled off a backing or carrier sheet.
In conventional die cutting apparatus for making labels, a web comprising a layer of pressure sensitive material on a layer of backing material is fed between an engraved die roll and an anvil roll which cooperate to cut through the layer of pressure sensitive material without cutting through the backing layer to form individual pressure sensitive labels on the backing layer. In such apparatus the die and anvil rolls are typically mounted for rotation about horizontal axes lying in the same vertical plane, which is perpendicular to the direction of web feed. With the die and anvil rolls so disposed with respect to one another and with respect to the direction of web feed, "crosscuts" (cuts extending transversely of the web) made by the blades on the engraved die roll are made across the entire width of the web in one instantaneous chopping motion. This type of cutting action is disadvantageous in that it necessitates the use of high cutting pressures, which tends to cause the die roll to arch away from the anvil roll and the web. As a result, the pressure sensitive label material may not be completely cut through, which prevents proper stripping of the waste label material from the backing following the die cutting operation. To avoid this problem, engraved die rolls used in the past have had to be sufficiently large in diameter to resist substantial arching. However, such die rolls are expensive due to the extensive amount of engraving required to make the roll.